Cystic fibrosis (also known as CF or mucoviscidosis) is one of the most common, fatal genetic diseases in humans. CF is an inherited autosomal recessive genetic disease that affects around 1 child in 2,500 live births. CF is caused by mutations in the cftr gene that encodes the cystic fibrosis transmembrane conductance regulator (CFTR protein) with activity as an epithelial chloride ion channel. As a result of impaired function of this protein, severe symptoms associated with respiratory and digestive systems and male reproductive system appear. To date, more than 1600 mutations in CFTR gene have been identified and described.
The CFTR gene mutations were classified into five classes based on the molecular mechanisms leading to the CFTR protein malfunction. The class I mutations contribute to the formation of proteins with incomplete length and usually involve the complete loss of its activity (e.g. G542X). Mutation in the class II lead to abnormal maturation of proteins in the endoplasmic reticulum and Golgi apparatus. The effect of these mutations is premature degradation of the protein. Hence, CFTR does not reach the cell membrane where it should perform its function (eg, ΔF508, ΔI507, S549R). The gene product having mutations of class III is properly synthesized, transported and incorporated into the cell membrane, but has decreased activity caused by abnormal regulation of the protein.
These mutations are frequently situated within one of the nucleotide binding domain. (eg. G551D/S). Mutations of class IV cause anomalies in the structure of the transmembrane protein and thereby reduce the conduction of chloride channel (e.g. R117H, R334W). Mutations altering the stability of mRNA represent a class V of the mutations of the CFTR gene (3849+10kbC->T,5T).
The most prevalent mutation present in at least one allele in approximately 90% of patients is a deletion of phenylalanine at position 508 of the CFTR amino acid sequence (ΔF508 CFTR). This is a classic example of class II mutation that causes premature degradation of the protein. This mutation is associated with water-electrolyte disturbances (among others with chloride anion flux out of a cell across the plasma membrane and the movement of sodium ions into the cell) and results in the appearance of pathological symptoms. Some of the most severe symptoms include congestion and increased mucus viscosity in the upper and lower airways leading to lung damage. These conditions create a favorable environment for development of bacterial infections caused by e.g. Pseudomonas aeruginosa. Moreover, malfunction of CFTR protein leads to obstruction of exocrine pancreatic ducts and related digestive disorders.
CFTR is a glycoprotein with 1480 amino acids and classified as an ABC (ATP-binding cassette) transporter. The protein consists of five domains. There are two nucleotide binding domains (NBD1 and NBD2), regulatory domain (RD) and two transmembrane domains (TMD1 and TMD2). The protein activity is regulated by cAMP-dependent Protein Kinase (PKA) which catalyze phosphorylation of regulatory domain (RD) and also by binding of two ATP molecules to NBD1 and NBD2 domains.
The disclosure in the patent application WO2007075901 (publ. 2007-07-05) relates to prodrugs of modulators of ABC transporters, particularly, CFTR modulators, compositions thereof, and methods therewith. An exemplary embodiment also relates to methods of treating ABC transporter mediated diseases using such modulators.
In U.S. Patent Publication No. 20080319008, compounds that increase activity (ion transport) of a mutant CFTR protein, and uses thereof are described. The disclosure also provides compositions, pharmaceutical preparations and methods increasing ion transport activity of a mutant CFTR protein, i.e. ΔF508 CFTR, G551D-CFTR, G1349D-CFTR or D1152H-CFTR, that are suitable in treating cystic fibrosis (CF). The compositions and pharmaceutical preparations of the disclosure may comprise one or more phenylglycine-containing compounds or sulfonamide-containing compounds or an analog or derivatives thereof.
In a publication WO2009051910, compounds that increase ion transport activity of a mutant CFTR protein, and uses thereof are described. The disclosure provides compositions, pharmaceutical preparations and methods for increasing activity of a mutant-CFTR. The compositions, pharmaceutical preparations and methods are notable for the study and treatment of disorders associated with mutant-CFTR, such as cystic fibrosis. The compositions and pharmaceutical preparations of the disclosure may comprise one or more phenylglycine-containing compounds, or an analog or derivative thereof.
U.S. Pat. No. 5,948,814 describes the use of genistein compound for treatment of CF. A method of treating cystic fibrosis by generating CFTR function in cells containing mutant CFTR and the therapeutic composition for treatment are described. The method of treatment comprises administering an effective amount of genistein, or genistein analogues and derivatives, to a patient afflicted with cystic fibrosis.
In U.S. Patent Publication No. 20040006127, a method for activation of the chloride is described. Fluorescein and derivatives have use in the treatment of a disease condition of a living animal body, including human, which disease is responsive to the activation of the CFTR chloride channels, for instance cystic fibrosis, disseminated brocheiectasis, pulmonary infections, chronic pancreatitis, male infertility and long QT syndrome.
In U.S. Patent Application No. 20080318984, compounds for correction of the cellular alteration of a mutant CFTR protein and uses thereof are described. The disclosure provides for compositions, pharmaceutical preparations and methods for correcting cellular processing of a mutant-CFTR protein (e.g., ΔF508 CFTR) that are notable for the treatment of cystic fibrosis. The compositions and pharmaceutical preparations of the disclosure may comprise one or more aminobenzothiazole-containing compounds, aminoarylthiazole-containing compounds, quinazolinylaminopyrimidinone-containing compounds, bisaminomethylbithiazole-containing compounds, or phenylaminoquinoline-containing compounds, or an analog or derivative thereof.
In a publication WO2009051909, compounds that improve the cellular alteration of a mutant CFTR protein and uses thereof are described. The disclosure provides compositions, pharmaceutical preparations and methods for increasing activity of a mutant-CFTR. The compositions, pharmaceutical preparations and methods are notable for the study and treatment of disorders associated with mutant-CFTR, such as cystic fibrosis. The compositions of the disclosure may comprise one or more bithiazole-containing compounds, or an analog or derivative thereof.
Phenylalanine 508 in CFTR protein occurs on the surface of NBD1 domain of CFTR. Current structural and biophysical studies reveal no significant differences between wild-domain protein, and ΔF508 mutant domain that may affect the folding kinetics and thermodynamic stability of CFTR protein. Solved crystal structures of both domains show only slight differences in the reorganization of the amino acids located near the site, which should be occupied by F508.
Each of the forgoing patents and publications are incorporated herein by reference in their entirety.